Buying a property? Don't overlook flood risk

The recent flooding in the top half of the South Island is horrible for all concerned, and our hearts go out to those who have been impacted. 

This incident has been one of many high-profile floods over the last couple of years across Aotearoa, and climate change projections indicate that as a country we can expect more extreme weather events. 

When engineers design infrastructure, one of the first things we assess is risk – especially from natural hazards like flooding. Yet, many property buyers overlook this critical factor. Here’s why you shouldn't:

1. Site selection is everything 

Civil and environmental engineers use topographic data, hydrological models and historical flood maps to determine safe building zones. If a site is prone to flooding, it’s often deemed unsuitable for critical infrastructure. However, there are many properties already located in these areas which were built well before we know what we do now, so do your homework. 

2. Structural integrity and long-term costs 

Flooding doesn’t just damage furniture – it undermines foundations, corrodes materials and accelerates structural decay. Even minor, repeated flooding can lead to major repair bills and insurance hikes. As the frequency of climate-related incidents occurs, you may even struggle to secure insurance in the future. 

3. Risk is quantifiable – and avoidable 

Engineers use return periods (e.g., 1-in-100-year flood) to estimate flood likelihood. This doesn’t mean it only happens every 100 years. These periods aren’t just theoretical – they're based on real data. If your future home is in a floodplain, the risk is measurable and real. 

4. Resilience is cheaper than recovery 

Designing for resilience – like elevating structures or using flood-resistant materials – is far more cost-effective than rebuilding. But the best resilience strategy? Avoid high-risk zones altogether. 

5. Health risk 

Homes that have been previously flooded and are damp can lead to health complications such as respiratory issues (especially for those with asthma or allergies). Floodwaters often contain sewage, chemicals and other hazardous substances, which may have some residue impacts. 

Bottom line:

Before you buy:

• ask the question of the selling agent 
• do your own desktop research in historical papers to see if there have been floods in the area previously and ask people that live/work nearby 
• source the flood modelling, which should be available from the local council. 

A great property isn’t worth the risk of being underwater – literally.